Solution-chemical syntheses of nano-structured Bi2Te3 and PbTe thermoelectric materials

In this work, nano-structured Bi2Te3 and PbTe thermoelectric materials were synthesized separately via solvothermal, hydrothermal and low-temperature aqueous chemical routes. X-ray diffraction (XRD), field-emission scanning-electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) were used to analyze the powder products. Results showed that the as-prepared Bi2Te3 samples were all single-phased and consisted of irregular spherical granules with diameters of similar to 30 nm whereas the PbTe samples were mainly composed of well-crystallized cubic crystals with average size of approximately 100 nm. Some nanotubes and nanorods were found in Bi2Te3 and PbTe samples, respectively; these were identified as Bi2Te3 nanotubes and PbTe nanorods by EDS analysis. Possible reaction mechanisms for these syntheses are discussed in detail herein.